This chapter looks at the link between two critical variables: the socialist movements and the Cold War system. The first is how the Korean War, the most significant byproduct of the Cold War, affected politics in general, as well as the socialist movement in particular. The second question is how the social democrats responded to structural barriers, such as conservative-cartel politics and repression. Regarding the detailed effects of the Cold War system on the politics of Korea, there was a complete evaporation of the advantageous conditions for the development of socialism. The authoritarian regime also poured their efforts into intensifying the conservative cartel in the party system. The Korean War resulted in an overdeveloped state and concomitantly caused a severely weakened civil society. In the wake of the Rhee government's political ordeals, the surviving social democrats constructed a social democrat party, the Progressive Party. The Cold War had two significant consequences for Korean politics.